Prior to the present invention, control valve devices of this general nature have been taught in the prior art. See, for example, German publication DE 33 45 697 A 1.
The control valve device shown and taught in DE 33 45 697 A1 includes a pressure medium inlet chamber which can be connected to a pressure medium source by a pressure medium inlet, and a pressure medium outlet chamber which is connected to a consumer, such as, the wheel brake cylinder of a vehicle.
The pressure medium outlet chamber can be connected on the one side to the pressure medium inlet chamber via a controlled inlet valve and, on the other side, to the atmosphere via an outlet valve. An actuating piston, which serves the purpose of actuating the outlet valve, limits the pressure medium outlet chamber with a first active surface, and a control chamber with a second active surface which is directed against the first active surface. The control chamber can be either connected to the atmosphere or to the pressure medium inlet chamber by a control valve.
The pressure in the pressure medium outlet chamber is applied to the actuating piston in an opening direction of the outlet valve, while the pressure in the control chamber is applied to the actuating piston in a closing direction of the outlet valve.
It is also conceivable not to connect the control valve to the pressure medium inlet chamber, but to connect it to a pressure medium supply line that communicates the pressure medium for the pressure medium inlet chamber, and connected to the pressure medium inlet of the control valve device, or to connect the control valve device to a pressure medium device connected before the pressure medium inlet and feeding into this pressure medium supply line.
The pressure is communicated to the consumer from a pressure medium source via a valve constructed as a combined inlet and outlet valve, such as a brake valve, and the opened inlet valve of the control valve device, while simultaneously, the pressure medium from the pressure medium inlet chamber, or the pressure medium in the pressure medium supply line connected to the pressure medium inlet, respectively, is applied to the control chamber associated with the outlet valve of the control valve device.
The pressure reduction in the consumer is, as well, achieved via the open inlet valve of the control valve device and the pressure medium inlet chamber, and the outlet valve of the combined inlet and outlet valve connected before the control valve device. The control chamber of the outlet valve of the control valve device is bled via the associated control valve, also via the pressure medium inlet chamber, or the pressure medium supply line feeding into the pressure medium inlet chamber.
Only if a regulated pressure reduction is desired in the consumer, the pressure in the consumer is decreased through the outlet valve of the control valve device by triggering the control valve associated with the outlet valve of the control valve device.
Thus, if a regulated pressure reduction is desired, the consumer is always bled through the inlet valve of the control valve device, the pressure medium inlet chamber, the pressure medium supply line running from the pressure medium inlet to the combined inlet and outlet valve, and through the outlet valve of the combined inlet and outlet valve.
The disadvantage of this control valve device, known to the art, is the fact that the process of bleeding the consumer requires a relatively long time period.